"Accent discrimination has been shown to be illegal when tied to national origin," says Walter Olson, a fellow at the Center for Legal Policy at the Manhattan Institute, a think tank based in New York City.

Federal law itself is silent about accents, but the US Equal Employment Opportunity Commission has determined that national-origin and race discrimination, which are prohibited by Title VII of the Civil Rights Act of 1964, include discrimination on the basis of language fluency, accent, and speaking manner.

Though legal experts say the law is still murky and accent cases are difficult to win, courts have ruled that a foreign accent that doesn't interfere with an employee's performance is not a legitimate basis for adverse treatment.

In May the EEOC won a case in which it forced a company to pay $29,500 to a woman it refused to hire for a receptionist position because of her Mexican accent. A month later, the agency won a case against Seattle-based Boeing in which the aerospace giant agreed to pay $37,500 to a Vietnamese-American whom it fired after allegedly subjecting him "to a hostile work environment, including comments about his accent."

That same month, on June 19, the agency claimed victory in a case against a New York-based music school. According to an agency document, a supervisor at the school allegedly subjected two Hispanic employees to a hostile work environment "including derogatory comments about their accents and pronunciation of English, and required them to speak only English at work." Damages: $60,000.

Social conservatives like Mr. Olson view accent discrimination as arbitrary expansion of workplace "protections" under Title VII, while more liberal theorists such as Georgetown University Law Professor Mary Matsuda believe that, because accents are an immutable characteristic, "discrimination against [them] is the functional equivalent of discrimination against foreign origin."

So what about regional accents? Might they, like nonnative accents, become a protected trait? In other words, might it one day be illegal to discriminate against a Southerner with a drawl?

"It's not completely frivolous to start thinking in that direction," says Ms. Matsuda. "It's not an issue simply of class. There's also a racial component. When someone says, 'I'll hire a white person, as long as they don't sound [lower class],' you're saying only a certain subset of that race is acceptable. It's like saying, 'We could hire a black person to work as long as they don't sound or act like a typical black person.' Most courts would recognize that as discrimination."

Matsuda also believes businesses should accommodate linguistic differences just as they would a disability. "If businesses make accommodations for employees who can't speak," she says, "is it unreasonable to ask them to make accommodations for people who speak differently?"